reed-solomon coding for ieee 802
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November 1999
Alantro Communications and SharewaveSlide 1
doc.: IEEE 802.11-99/250
Submission
Reed-Solomon Codingfor IEEE 802.11
• Chris Heegard & Matthew Shoemake– Alantro Communications
• Rajugopal Gubbi– Sharewave
November 1999
Alantro Communications and SharewaveSlide 2
doc.: IEEE 802.11-99/250
Submission
Presentation Slide 1 Dr. Rajugopal Gubbi
Nov. 1999 IEEE P802.11-99/
FEC for Streams
• All streams can not be treated in the same way at MAC
• Different streams have different transmission requirements. Eg.,
• High bandwidth requirement for stream like video prohibit
retransmissions.
• Latency constraints in streams like voice limits the number of
retransmissions attempts.
• Other streams like audio, interactive media have different
retransmission requirements
• Error correction significantly improves the data throughput.
November 1999
Alantro Communications and SharewaveSlide 3
doc.: IEEE 802.11-99/250
Submission
Presentation Slide 2 Dr. Rajugopal Gubbi
Nov. 1999 IEEE P802.11-99/
Feasibility of Reed Soloman Coder
• Well known technology
• Already used by standards
• IEEE 802.14/MCNS
• DVB/DBS
• Etc...
• Commercially available
• RS (255, 239), tmax=8 cores are under 20K gates
November 1999
Alantro Communications and SharewaveSlide 4
doc.: IEEE 802.11-99/250
Submission
Presentation Slide 3 Dr. Rajugopal Gubbi
Nov. 1999 IEEE P802.11-99/
FEC Field Results
x1
x3
x5
x7
x9
0x1x
2x3x
4x5x
6x7x
8x9x
0
5
10
15
20
25
30
PER [%]
Un corrected PER242.4 K Packet Cluster
x1
x3
x5
x7
x9
0x1x
2x3x
4x5x
6x7x
8x9x
Corrected PER242.4 K Packet Cluster
Before FEC After FEC* 4 sq. /ft MatrixTest Area* 45ft Transmit Distance
November 1999
Alantro Communications and SharewaveSlide 5
doc.: IEEE 802.11-99/250
Submission
Parameters of Reed-Solomon Codes forMPEG Video Packets
• GF256 (8 bit byte symbols)
• (n <= 257, k = n-2*t, d = 2*t+1)– Can correct t errors
• MPEG-2 Packets, k = 188, n = 188+2*t
November 1999
Alantro Communications and SharewaveSlide 6
doc.: IEEE 802.11-99/250
Submission
CCK at 11 Mbps, Es/No
November 1999
Alantro Communications and SharewaveSlide 7
doc.: IEEE 802.11-99/250
Submission
PBCC at 11 Mbps, Es/No
November 1999
Alantro Communications and SharewaveSlide 8
doc.: IEEE 802.11-99/250
Submission
CCK at 11 Mbps, Eb/No
November 1999
Alantro Communications and SharewaveSlide 9
doc.: IEEE 802.11-99/250
Submission
PBCC at 11 Mbps, Eb/No
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